Problems with µ, displaying ţ with sisetup option (for combination of siunitx, fontspec and kpfonts)
This seems to work.
The primary/only relevant? change is explicitly setting math-micro
to \mu
via \sisetup
\documentclass{article}
\usepackage{fontspec}
\usepackage[T1]{fontenc}
\usepackage[uprightgreeks,partialup]{kpfonts}
\usepackage{siunitx}
\sisetup{
math-micro = \mu,
}
\begin{document}
\SI{1}{\micro \meter}
\SI{1}{\micro \gram}
\SI{1}{\kilo \gram}
\SI{1}{\nano \gram}
\si{\gram}
\begin{equation}
\frac{\partial Q}{\partial t} = \frac{\partial s}{\partial t} % just testing the partial ups
\end{equation}
\si{\micro \gram}
\end{document}